React Native CDP Status

Debugger Domain

Debugger domain exposes JavaScript debugging capabilities. It allows setting and removing breakpoints, stepping through execution, exploring stack traces, etc.

Methods

Debugger.disable #

Disables debugger for given page.

Handles Debugger.disable request @cdp Debugger.disable If domain is already disabled, will return success.

facebook/hermes/…/DebuggerDomainAgent.h:111

Debugger.enable #

Enables debugger for the given page. Clients should not assume that the debugging has been enabled until the result for this command is received.

Handles Debugger.enable request @cdp Debugger.enable If domain is already enabled, will return success.

facebook/hermes/…/DebuggerDomainAgent.h:108

Parameters

maxScriptsCacheSize
Optional

number

The maximum size in bytes of collected scripts (not referenced by other heap objects) the debugger can hold. Puts no limit if parameter is omitted.

Experimental

Return object

debuggerId

Runtime.UniqueDebuggerId

Unique identifier of the debugger.

Experimental

Debugger.evaluateOnCallFrame #

Evaluates expression on a given call frame.

In V8, @cdp Debugger.evaluateOnCallFrame populates the result field with the exception value.

facebook/hermes/…/DebuggerDomainAgent.cpp:538

Parameters

callFrameId

CallFrameId

Call frame identifier to evaluate on.

expression

string

Expression to evaluate.

objectGroup
Optional

string

String object group name to put result into (allows rapid releasing resulting object handles using releaseObjectGroup).

includeCommandLineAPI
Optional

boolean

Specifies whether command line API should be available to the evaluated expression, defaults to false.

silent
Optional

boolean

In silent mode exceptions thrown during evaluation are not reported and do not pause execution. Overrides setPauseOnException state.

returnByValue
Optional

boolean

Whether the result is expected to be a JSON object that should be sent by value.

generatePreview
Optional

boolean

Whether preview should be generated for the result.

Experimental

throwOnSideEffect
Optional

boolean

Whether to throw an exception if side effect cannot be ruled out during evaluation.

timeout
Optional

Runtime.TimeDelta

Terminate execution after timing out (number of milliseconds).

Experimental

Return object

result

Runtime.RemoteObject

Object wrapper for the evaluation result.

exceptionDetails
Optional

Runtime.ExceptionDetails

Exception details.

Debugger.pause #

Stops on the next JavaScript statement.

Debugger.removeBreakpoint #

Removes JavaScript breakpoint.

Parameters

breakpointId

BreakpointId

Debugger.resume #

Resumes JavaScript execution.

Parameters

terminateOnResume
Optional

boolean

Set to true to terminate execution upon resuming execution. In contrast to Runtime.terminateExecution, this will allows to execute further JavaScript (i.e. via evaluation) until execution of the paused code is actually resumed, at which point termination is triggered. If execution is currently not paused, this parameter has no effect.

Debugger.setBreakpoint #

Sets JavaScript breakpoint at a given location.

Parameters

location

Location

Location to set breakpoint in.

condition
Optional

string

Expression to use as a breakpoint condition. When specified, debugger will only stop on the breakpoint if this expression evaluates to true.

Return object

breakpointId

BreakpointId

Id of the created breakpoint for further reference.

actualLocation

Location

Location this breakpoint resolved into.

Debugger.setBreakpointByUrl #

Sets JavaScript breakpoint at given location specified either by URL or URL regex. Once this command is issued, all existing parsed scripts will have breakpoints resolved and returned in locations property. Further matching script parsing will result in subsequent breakpointResolved events issued. This logical breakpoint will survive page reloads.

Parameters

lineNumber

integer

Line number to set breakpoint at.

url
Optional

string

URL of the resources to set breakpoint on.

urlRegex
Optional

string

Regex pattern for the URLs of the resources to set breakpoints on. Either url or urlRegex must be specified.

scriptHash
Optional

string

Script hash of the resources to set breakpoint on.

columnNumber
Optional

integer

Offset in the line to set breakpoint at.

condition
Optional

string

Expression to use as a breakpoint condition. When specified, debugger will only stop on the breakpoint if this expression evaluates to true.

Return object

breakpointId

BreakpointId

Id of the created breakpoint for further reference.

locations

array[ Location ]

List of the locations this breakpoint resolved into upon addition.

Debugger.setBreakpointsActive #

Activates / deactivates all breakpoints on the page.

Handles Debugger.setBreakpointsActive @cdp Debugger.setBreakpointsActive Allowed even if domain is not enabled.

facebook/hermes/…/DebuggerDomainAgent.h:146

Parameters

active

boolean

New value for breakpoints active state.

Debugger.setPauseOnExceptions #

Defines pause on exceptions state. Can be set to stop on all exceptions, uncaught exceptions, or caught exceptions, no exceptions. Initial pause on exceptions state is none.

Parameters

state

string

Pause on exceptions mode.

Allowed values: none, caught, uncaught, all

Debugger.stepInto #

Steps into the function call.

Parameters

breakOnAsyncCall
Optional

boolean

Debugger will pause on the execution of the first async task which was scheduled before next pause.

Experimental

skipList
Optional

array[ LocationRange ]

The skipList specifies location ranges that should be skipped on step into.

Experimental

Debugger.stepOut #

Steps out of the function call.

Debugger.stepOver #

Steps over the statement.

Parameters

skipList
Optional

array[ LocationRange ]

The skipList specifies location ranges that should be skipped on step over.

Experimental

Debugger.setBlackboxedRanges Experimental#

Makes backend skip steps in the script in blackboxed ranges. VM will try leave blacklisted scripts by performing 'step in' several times, finally resorting to 'step out' if unsuccessful. Positions array contains positions where blackbox state is changed. First interval isn't blackboxed. Array should be sorted.

Parameters

scriptId

Runtime.ScriptId

Id of the script.

positions

array[ ScriptPosition ]

Debugger.setBlackboxPatterns Experimental#

Replace previous blackbox patterns with passed ones. Forces backend to skip stepping/pausing in scripts with url matching one of the patterns. VM will try to leave blackboxed script by performing 'step in' several times, finally resorting to 'step out' if unsuccessful.

Parameters

patterns

array[ string ]

Array of regexps that will be used to check script url for blackbox state.

skipAnonymous
Optional

boolean

If true, also ignore scripts with no source url.

Events

Debugger.paused #

Fired when the virtual machine stopped on breakpoint or exception or any other stop criteria.

Although the documentation lists the "data" field as optional for the @cdp Debugger.paused event: https://chromedevtools.github.io/devtools-protocol/tot/Debugger/#event-paused it is accessed unconditionally by the front-end when the pause reason is "exception". "data" is passed in as "auxData" via: https://github.com/facebookexperimental/rn-chrome-devtools-frontend/blob/9a23d4c7c4c2d1a3d9e913af38d6965f474c4284/front_end/core/sdk/DebuggerModel.ts#L994 and "auxData" stored in a DebuggerPausedDetails instance: https://github.com/facebookexperimental/rn-chrome-devtools-frontend/blob/9a23d4c7c4c2d1a3d9e913af38d6965f474c4284/front_end/core/sdk/DebuggerModel.ts#L642 which then has its fields accessed in: https://github.com/facebookexperimental/rn-chrome-devtools-frontend/blob/main/front_end/panels/sources/DebuggerPausedMessage.ts#L225 If the "data" ("auxData") object is absent, accessing its fields will throw, breaking the display of pause information. Thus, we always populate "data" with an object. The "data" field has no schema in the protocol metadata that we use to generate message structures, so we need to manually construct a JSON object here. The structure expected by the front-end (specifically, the "description" field) can be inferred from the field access at the URL above. The front-end does gracefully handle missing fields on the "data" object, so we can consider the "description" field optional.

facebook/hermes/…/DebuggerDomainAgent.cpp:697

Parameters

callFrames

array[ CallFrame ]

Call stack the virtual machine stopped on.

reason

string

Pause reason.

Allowed values: ambiguous, assert, CSPViolation, debugCommand, DOM, EventListener, exception, instrumentation, OOM, other, promiseRejection, XHR, step

data
Optional

object

Object containing break-specific auxiliary properties.

hitBreakpoints
Optional

array[ string ]

Hit breakpoints IDs

asyncStackTrace
Optional

Runtime.StackTrace

Async stack trace, if any.

asyncStackTraceId
Optional

Runtime.StackTraceId

Async stack trace, if any.

Experimental

asyncCallStackTraceId
Optional

Runtime.StackTraceId

Never present, will be removed.

ExperimentalDeprecated

Debugger.resumed #

Fired when the virtual machine resumed execution.

Debugger.scriptParsed #

Fired when virtual machine parses script. This event is also fired for all known and uncollected scripts upon enabling debugger.

Parameters

scriptId

Runtime.ScriptId

Identifier of the script parsed.

url

string

URL or name of the script parsed (if any).

startLine

integer

Line offset of the script within the resource with given URL (for script tags).

startColumn

integer

Column offset of the script within the resource with given URL.

endLine

integer

Last line of the script.

endColumn

integer

Length of the last line of the script.

executionContextId

Runtime.ExecutionContextId

Specifies script creation context.

hash

string

Content hash of the script, SHA-256.

buildId

string

For Wasm modules, the content of the build_id custom section. For JavaScript the debugId magic comment.

executionContextAuxData
Optional

object

Embedder-specific auxiliary data likely matching {isDefault: boolean, type: 'default'|'isolated'|'worker', frameId: string}

isLiveEdit
Optional

boolean

True, if this script is generated as a result of the live edit operation.

Experimental

sourceMapURL
Optional

string

URL of source map associated with script (if any).

hasSourceURL
Optional

boolean

True, if this script has sourceURL.

isModule
Optional

boolean

True, if this script is ES6 module.

length
Optional

integer

This script length.

stackTrace
Optional

Runtime.StackTrace

JavaScript top stack frame of where the script parsed event was triggered if available.

Experimental

codeOffset
Optional

integer

If the scriptLanguage is WebAssembly, the code section offset in the module.

Experimental

scriptLanguage
Optional

Debugger.ScriptLanguage

The language of the script.

Experimental

debugSymbols
Optional

array[ Debugger.DebugSymbols ]

If the scriptLanguage is WebAssembly, the source of debug symbols for the module.

Experimental

embedderName
Optional

string

The name the embedder supplied for this script.

Experimental

resolvedBreakpoints
Optional

array[ ResolvedBreakpoint ]

The list of set breakpoints in this script if calls to setBreakpointByUrl matches this script's URL or hash. Clients that use this list can ignore the breakpointResolved event. They are equivalent.

Experimental

Debugger.breakpointResolved Deprecated#

Fired when breakpoint is resolved to an actual script and location. Deprecated in favor of resolvedBreakpoints in the scriptParsed event.

Parameters

breakpointId

BreakpointId

Breakpoint unique identifier.

location

Location

Actual breakpoint location.

Types

Debugger.DebugSymbols #

Debug symbols available for a wasm script.

Type: object

Properties

type

string

Type of the debug symbols.

Allowed values: SourceMap, EmbeddedDWARF, ExternalDWARF

externalURL
Optional

string

URL of the external symbol source.

Debugger.ScriptLanguage #

Enum of possible script languages.

Type: string

Allowed values: JavaScript, WebAssembly